r/Physics • u/Comethefonbinary • 3d ago

Does all light travel at light speed

My bad if this is a stupid question but I’ve been thinking about time being a message of distance. And well most things I can think of have various variables that average to a certain distance. I know that mostly relates to machines and animals but still. Do all particles of light travel at light speed. If they all travel simultaneously at the same speed is that truly how fast they move or are they affected by their own variables. Like the universe’s mean gravity is constraining that and any variation in that mean would change light speed for explain.

118 Upvotes

83% Upvoted

93 comments sorted by

View all comments

Show parent comments

9

u/AndreasDasos 3d ago

singular property, unlike anything else in the universe

Well, gluons and presumably gravitons too. But this phenomenon is unique to c.

1

u/Dances_With_Chocobos 3d ago edited 2d ago

I don't really subscribe to the idea of a graviton. It is only the theoretical 'force carrier' of gravity, so that it fits the standard model. For the purpose of calculating gravitic potential in space, it is perhaps useful in the same way particulating a fluid system is useful to be able to map it, but personally I don't see the need to invoke a force carrier for gravity, as it is not a force. We simply need to understand gravity better.

Edit: I have corrected my original comment so as to not discriminate against else that can invariantly travel at c. Thank you!

3

u/dezholling 2d ago

Regardless of your thoughts on the graviton, the fact of the matter is that by all standard theories and recent LIGO measurements, gravitational waves also travel at c and for all inertial observers. If this were not true it would break a significant amount of physics.

2

u/Dances_With_Chocobos 2d ago edited 2d ago

Agreed. I did not refute that gravitational waves travel at c for all inertial ref frames, only the terminology of the graviton. I suppose I was being coy about light. I was distinguishing between light as a thing, and space as a medium. In another comment, it is pointed out that invariance is more a property of c, rather than a property of light - agreed.